With the wide proliferation of mobile terminals, also called cellular or personal communication system (PCS) terminals, or pervasive computing devices, users have demanded ways to make the use of such devices less obtrusive in public. Consequently, many such devices are today equipped with a “silent alert” function. Such a silent alert function involves the use of a “non-audible” alerting device built into the terminal. This device typically alerts the user to an incoming call, or possibly other events, with vibrations produced by a mechanism such as a piezoelectric vibrator or a motor with an offset mass. Of course, for such an alerting mechanism to be effective the mobile terminal that contains it must be in physical contact with the user when a call is received.
In parallel with the above developments, “Bluetooth” technology has made it practical to connect accessories to a mobile terminal via a short-range wireless interface. Bluetooth is a standard for short-range wireless connections between various types of microprocessor based devices. Bluetooth supports connectivity between computers and peripherals, computers and wireless terminals, and wireless terminals and peripherals, without the use of linking cables. The Bluetooth standard consists of a core specification and supporting documents, including various device profiles that specify signaling required for specific types of devices. The latest core specification is “Specification of the Bluetooth System; Core, version 1.1,” and the latest profiles are contained in “Specification of the Bluetooth System; Profiles, version 1.1,” both published Feb. 2, 2001 by the Bluetooth special interest group (SIG), Inc., and which are incorporated herein by reference. The Bluetooth SIG is a consortium of companies such as Ericsson, IBM, Intel, Microsoft, Motorola, and others which promulgates Bluetooth standards.
Hands-free headsets have been among the first devices to make use of Bluetooth technology. Such hands-free headsets implement a hands-free Bluetooth profile. Bluetooth connectivity for such headsets means that a headset does not need to be connected via wires to a mobile terminal or other Bluetooth-enabled device. Instead, a user of the headset must simply be within about thirty feet of the terminal device. The Bluetooth standards refer to the terminal device as an “audio gateway”. When a terminal in this case wants to alert a user to an incoming call or other event, it plays a ring tone through the ear-piece of the headset. However, if the user does not happen to have the ear-piece inserted or covering his ear at the particular time an alert is received then the user may not be aware of the event, since the terminal could be some distance away and possibly enclosed in a briefcase or switched into a silent alert mode of operation.